Processing and Mechanical Properties of Starch and PVA Composite Reinforced by MCC

Abstract:

Article Preview

The thermoplastic processing and mechanical properties of starch and polyvinyl alcohol (PVA) composites reinforced with microcrystal cellulose (MCC) were investigated. Glycerol with 30 wt% was chosen as the plasticizer for starch and PVA, respectively. MCC with 2 wt% was used to reinforce the starch/PVA composite. The results showed that the mechanical properties of the obtained starch/PVA blend were best when the glycerol content was 30% of starch and 20% of PVA, and the weight ratio of PVA and starch was 4/6 (wPVA/wstarch). After the addition of MCC, the mechanical properties of the starch/PVA blends were improved, and the tensile strength was increased by 52%. Moreover, it was confirmed by rheological measurements that MCC could interact with the composite materials, which results in the improvement of the mechanical strength of the starch/PVA composites.

Abstract: Porous C/C composite with certain porosity prepared by Chemical vapor infiltration
(CVI) was chosen as the preforms to develop the C/C-SiC composites through precursor infiltration
and pyrolysis(PIP), using PCS (polycarbosilane) as the precursor and divinylbenzene as solvent and
cross-linking reagent for PCS. The effect of the infiltration solution with different PCS/DVB ratio on
the final density, microstructure, and mechanical properties of composites was investigated and the
proper PCS/DVB ratio to prepare the C/C-SiC composites was suggested. The experimental results
showed that the final densities and the mechanical properties of the composites were close related to
the PCS/DVB ratio. Higher PCS/DVB ratio resulted in higher final density and better mechanical
properties, but not the highest PCS/DVB ratio could get the best mechanical properties. The main
reason is that too high PCS/DVB ratio will make the infiltration process become difficult and lead to
the formation of lots of pores in the final composite, at last lowers the mechanical properties. It is
believed that the 50% PCS content is proper to prepare the C/C-SiC composites. The composite from
50% PCS infiltration solution could get the final density of1.696g/cm3, the flexural strength of
171Mpa, and shearing strength of 21.6Mpa, which are the best mechanical results among the obtained
materials.

Abstract: In this study, the effect of combined environmental factors such as ultraviolet ray, high
temperature and high moisture on mechanical and thermal analysis properties of glass fabric and
phenolic composites are evaluated through a 2.5KW accelerated environmental aging tester. The
environmental factors such as temperature, moisture and ultraviolet ray applied of specimens. A
xenon-arc lamp is utilized for ultraviolet light and exposure time of up to 3000 hours are applied.
Several types of specimens - tensile, bending, and shear specimens that are warp direction and fill
direction are used to investigate the effects of environmental factors on mechanical properties of the
composites. Mechanical degradations for tensile, bending and shear properties are evaluated
through a Universal Testing Machine (UTM). Also, storage shear modulus, loss shear modulus and
tan δ are measured as a function of exposure time through a Dynamic Mechanical Analyzer (DMA).
From the experimental results, changes in material properties of glass fabric and phenolic
composites are shown to be slightly degraded due to combined environmental effects.

Abstract: We investigated the effects of amount of antioxidants variability on selected mechanical and physical properties of wood plastic composites. Recycled high density polyethylene (rHDPE) and natural fibers were compounded into pellets by compounder, then the pellets were extruded using co-rotating twin-screw extruder and test specimens were prepared by hot and cold press process. From the study, samples with 0.5 wt% of antioxidants produce the highest strength and elasticity of composites. The effect of antioxidants presence on water uptake is minimal.

Abstract: Hybrid composites were prepared by incorporating oil palm fruit bunch (OPFB) fibre in the mixture of clay and polypropylene as secondary filler. OPFB and MAPP loadings were varied to investigate it effects on the performance. Tensile and impact tests were performed on the hybrid composites to evaluate their mechanical performances. Water absorption and thermal degradation tests were also conducted on the hybrid composites. Results indicated that the incorporation of OPFB in PP/PPnanoclay has decreased the thermal stability of hybrid composites. Tensile modulus of hybrid composites increased as the OPFB loading increases and further increased with the increasing of MAPP loading. Generally the tensile strength has decreased with the addition of OPFB, however slight increased was observed when the MAPP loading was increased. The impact strength has also increased with the increasing of OPFB for higher MAPP loading.

Abstract: The rheological properties of the low density polyethylene (LDPE)/palm kernel shell (PKS) composites were studied by using a melt flow indexer. The silane treated and untreated composites were investigated. Both of the composites were further varied by amount of filler loading from 10 to 40 php. The testing temperature of composites varied from 180 to 210 °. It was found out that the MFI values of the composites increased with temperature but decreased with a rise of filler loading. The treated LDPE/PKS composites exhibited lower MFI values compared to untreated composites, which indicated the increase of viscosity. Thus, a better adhesion between the LDPE matrix and PKS was established. The effect of temperature on the viscosity of LDPE/PKS composites was found to obey the Arrhenius equation. The results showed that the activation energy of the composites increased with the increase of filler loading. However, at similar filler loading, the silane treated composites showed lower activation energy compared to untreated composites, leading to the reduction of their temperature sensitivity.